1. Technical Field
The invention relates to a roll paper supplying device and a recording apparatus.
2. Related Art
As an example of roll paper supplying device, a paper supplying device which includes a torque limiter connected to a spool shaft for supporting a roll paper is known as disclosed in JP-A-2012-193032. The paper supplying device includes the spool shaft with a flange on which the roll paper is attached, a driven gear provided on one end of the spool shaft, a driving motor that feeds the roll paper in a reverse direction for a start operation, a driving gear provided on an output shaft of the driving motor, and a rotational force driving mechanism disposed between the driving gear and the driven gear. Further, the rotational force driving mechanism is formed by a gear train composed of a plurality of gears. In this gear train, a one-way clutch that allows a power to be transmitted only in reverse rotation of the roll paper, and a torque limiter that brakes the rotation of the roll paper are incorporated. As the roll paper is fed out by a registration roller and a pressure roller, the spool shaft, the driven gear and part of the gear train rotate while applying a back tension to the roll paper fed out via the spool shaft.
In such a paper supplying device, the torque limiter needs to be provided at a position where the roll paper is supported in order to ensure a stable tension to be applied to the roll paper. When the torque limiter is provided at a position where the roll paper is supported, a tension applied to the roll paper changes in inversely proportional to a diameter of the roll regardless of a constant braking torque, since the diameter of the roll gradually decreases as the roll paper is fed out. The tension applied to the roll paper is small when the diameter of the roll is large, and increases as the diameter of the roll becomes small. As a result, a constant tension is not applied to the roll paper.